Conjunctivitis, commonly called “pink eye”, refers to inflammation or infection of the conjunctiva. The conjunctiva is the thin mucous membrane that lines the inside of the eyelids and the surface of the globe up to the limbus, where the sclera and cornea meet. It is divided into the following two portions: the bulbar portion, covering the globe, and the tarsal portion, covering the lids. It is usually transparent; however, it can become injected and pink or red when inflamed, leading to the colloquial term “pink eye”. Conjunctivitis can vary in severity, ranging from mild redness associated with tearing to subconjunctival hemorrhage with purulent discharge and edema of the conjunctiva or eyelid.

The classification of pediatric conjunctivitis is typically by etiology, broadly categorized into infectious and non-infectious causes. Most cases of pediatric conjunctivitis are infectious, either bacterial or viral. Non-infectious conjunctivitis includes allergic conjunctivitis as well as conjunctivitis due to foreign bodies, environmental causes, or contact lens overwear. There are certainly other, more serious, causes of pink eye such as cellulitis, uveitis, endophthalmitis, and acute glaucoma, which may have a similar presentation; however, those causes are beyond the scope of this discussion.

The majority of cases of pediatric conjunctivitis are managed by primary care providers rather than eye-specific providers ^[1]. There are no widely accepted guidelines for the management of conjunctivitis in children and widely varying practices from clinician to clinician have been noted ^[2].

2. Making the Diagnosis

When a child presents with “pink eye”, the evaluation should first start with a review of the history, signs, and symptoms to determine the etiology. It is essential to obtain information such as the length of symptoms, whether one or both eyes are affected, and a description of drainage from the eye(s), if any. Associated symptoms may also give a clue for the etiology, particularly if there are co-occurring viral symptoms such as a cough, sore throat, fever, or rash. If the patient has had trauma to the eye or if their symptoms have a predominance for certain times of the year, this may also provide guidance toward understanding the etiology. Depending on the age of the child, it may be appropriate to ask if they have noticed any changes to their vision or if a foreign body sensation is present. The physical examination should always begin with a vision measurement, testing each eye separately with a Snellen chart. For children too young to participate with a Snellen chart test, near vision can be broadly measured by seeing if patients can focus on a book, toy, or their caregiver. If visual acuity appears to be affected, a referral should be made to a pediatric ophthalmologist for further evaluation. Physical examination should continue with the use of a penlight. When examining the pupils and anterior segment, attention should be given to the size of the pupil and if it is reactive to light. If there is discharge present, it is important to note the consistency, color, and amount of it. In addition, the conjunctiva should be examined to determine if the entire conjunctiva is affected or if there is a specific area that is more erythematous. For clinicians that are comfortable with it, inverting the eyelid can also provide clues to the etiology. A fundoscopic exam is not typically useful in differentiating between the various etiologies. Laboratory testing and imaging are also not typically necessary for cases of uncomplicated conjunctivitis. A thorough history and physical exam can give clues to the etiology and management of “pink eye,” respectively. However, it is important to note that clinical presentation is often non-specific. While significant research has been devoted to predicting the causative agent based on symptoms, few studies have demonstrated the ability to successfully achieve this. A 2003 meta-analysis did not find any evidence for the diagnostic usefulness of clinical signs and symptoms to differentiate bacterial from viral conjunctivitis ^[3]. However, a more recent meta-analysis from 2022 found that bacterial conjunctivitis may in fact be the more common cause of conjunctivitis in children ^[4], with as many as 70% of conjunctivitis cases in children. The same meta-analysis found that adults presenting with acute conjunctivitis had an identified bacterial etiology much less often, only about 16% of the time. A multi-center study of adults with bacterial conjunctivitis demonstrated that the symptoms can widely vary. Of those patients with positive bacterial cultures, 65% had burning, 58% had itching, and 35% had serous or no discharge at all ^[5]. Associated symptoms may give clinical clues to the bacterial, viral, or other causes of conjunctivitis. For example, the presence of mucopurulent discharge or otitis media is suggestive of a bacterial etiology. Concomitant pharyngitis, pre-auricular lymphadenopathy, and known contacts with red eye all suggest viral etiologies ^[4].

3. Treatment

3.1. Bacterial Conjunctivitis

The vast majority of cases of bacterial conjunctivitis are self-limiting, lasting 7 to 10 days without treatment. While antibiotics have been shown to decrease the duration of symptoms, no differences in sight threatening outcomes have been observed between treatment and non-treatment groups. In a meta-analysis consisting of 11 randomized clinical trials and 3673 patients, there was a 10% increase in the rate of clinical improvement for patients who received early antibiotic treatment compared with the placebo group ^[6]. A recent study from Finland supported this, showing a more rapid clinical cure in patients treated with antibiotic eye drops, from a mean of 4.0 days with a placebo to a mean of 3.8 days with moxifloxacin treatment ^[7]. Antibiotics are not without risk, with adverse drug reactions reported by 8% of patients using ophthalmic antibiotics ^[8]. In addition, studies have shown acquired resistance to pathogenic bacteria in the conjunctiva of children prescribed antibiotics ^[9][10]. While antibiotics are not required for all cases, contact lens wearers should always be treated with antibiotics due to the increased risk of infection with gram negative organisms and subsequent keratitis. With that in mind, no treatment, a delayed treatment approach, and immediate treatment all are appropriate responses to suspected uncomplicated bacterial conjunctivitis ^[11]. A study of 20 clinicians in Colorado demonstrated that the main drivers behind choosing to prescribe or withhold antibiotics were the patient’s clinical presentation, family expectations, antibiotic stewardship concerns, diagnostic uncertainty, and daycare and school policies. They noted that the most critical features to help clinicians differentiate between viral and bacterial conjunctivitis were the association with other upper respiratory symptoms and laterality ^[2]. Overprescribing of antibiotics is common, particularly in cases where the etiology is uncertain. The COVID-19 pandemic worsened this, likely due to the increase in children being treated over the telephone or virtually without being seen directly by a physician ^[12]. In many cases, families will assert that treatment with antibiotics is necessary for their child to return to school or daycare ^[2]. School specific policies widely vary from state to state, but the American Academy of Pediatrics specifically notes that antibiotics should not be required for return to care ^[2][13]. If treatment is desired, initial treatment would begin with erythromycin ointment or trimethoprim-polymyxin B ophthalmic drops. Symptoms would be expected to improve within one to two days.

3.2. Viral Conjunctivitis

Treatment of viral conjunctivitis, including COVID-19 conjunctivitis, is primarily symptomatic through the use of cool compresses and lubricating artificial tears. Adenoviral conjunctivitis is generally self-limited and highly contagious. A study of 56 adults with adenoviral conjunctivitis who were treated in clinics with a single drop of 5% povidone iodine demonstrated reduced viral load and a more rapid improvement in symptoms ^[14]. While not standard practice at this time, this is likely to be an emerging therapy if larger studies in the future can demonstrate similar symptomatic improvement. Patients should be educated on the ways to prevent the spread of viral conjunctivitis, such as avoiding shared towels or bed linens and washing their hands frequently. In fact, a study of 26 adults with conjunctivitis showed that 46% had positive adenovirus cultures grown from swabs of their hands ^[15]. Patients should be encouraged to make every attempt to minimize contact with others for 10 to 14 days from symptom onset ^[11].

3.3. Allergic Conjunctivitis

Treatment of allergic conjunctivitis consists of minimizing exposure to the allergen and controlling symptoms. Topical lubricants such as artificial tears or saline can be used to physically wash out the offending allergens. Mild allergic conjunctivitis can be treated with topical antihistamine agents, preferably second generation topical H1-receptor antagonists ^[16]. If persistent, ophthalmic drops that have both antihistamine activity and mast cell stabilizing properties, such as azelastine or olopatadine, can be used. A step-wise approach may be helpful, starting with topical lubricant, then antihistamines, and finally topical steroids ^[17]. Of note, topical steroids should only be used in a time-limited fashion, limited to 7 days or less. Systemic antihistamines are frequently used to reduce histamine release, improving both allergic conjunctivitis and other systemic symptoms.

3.4. Foreign Body

Many foreign bodies are superficial and benign, yet cause significant pain. All patients with suspected corneal foreign bodies should receive a complete eye examination. Topical NSAIDs such as ketorolac and oral analgesics have been shown to reduce pain and improve patients’ tolerance of the examination ^[18]. If a foreign body is identified, removal should be completed as soon as possible, usually within 24 h. If foreign body accessibility is limited, emergent foreign body removal should be completed by an ophthalmologist ^[19]. Upon removal, topical prophylactic antibiotics should be prescribed to prevent superimposed infection. Even if a foreign body is not identified, individuals wearing contact lenses should receive anti-pseudomonal coverage such as ciprofloxacin or gentamicin. For those without contacts, topical bacitracin or erythromycin have been utilized; however, the efficacy of prophylactic antibiotics is still uncertain. In the United States, ocular prophylaxis against neonatal conjunctivitis with 0.5% erythromycin ophthalmic ointment is the common practice. However, there is an ongoing conversation about the necessity of ocular prophylaxis, given that the rates of gonorrhea in pregnant people have decreased steadily since the 1970s ^[20]. All pregnant people are screened throughout their pregnancy; thus, the majority of neonates are treated prophylactically despite a minimal risk of them developing gonococcal conjunctivitis ^[21]. The data surrounding the efficacy of erythromycin ointment on gonococcal conjunctivitis are limited and there is concern for N. gonorrhoeae developing resistance to erythromycin ^[21]. Despite this, the United States Preventative Service Task Force (USPSTF) continues to recommend erythromycin prophylaxis for all newborns. In the USPSTF’s most recent reaffirmation statement on ocular prophylaxis, they cite that the rate of gonococcal neonatal conjunctivitis is currently estimated to be 0.4 cases per 100,000 live births per year and without ocular prophylaxis, transmission rates are as high as 30% to 50% ^[20]. Despite the fact that all pregnant people are screened for N. gonorrhoeae, approximately 6.2% of individuals in the United States do not receive prenatal care, thus would have an increased risk of unknowingly transmitting N. gonorrhoeae to their newborn ^[20]. With this in mind, erythromycin ophthalmic ointment remains the standard of care. One side effect that is important for clinicians to be aware of is that erythromycin ophthalmic ointment can lead to a form of chemical conjunctivitis in the first 24 h of life ^[21]. Neonatal chemical conjunctivitis, whether from erythromycin or silver nitrate, is typically self-limited and resolves within two to four days ^[22]. For other cases of conjunctivitis, the treatment depends on the etiology. For conjunctivitis caused by C. trachomatis, treatment is typically erythromycin ophthalmic drops plus oral erythromycin for a total course of two to three weeks ^[11]. For cases of conjunctivitis caused by N. gonorrhoeae, the treatment is a third-generation cephalosporin, such as ceftriaxone, in a single dose. This is started along with normal saline irrigation to the eyes with hopes to remove the mucopurulent discharge typically present. As with most cases, neonates treated for gonococcal conjunctivitis should also be treated for chlamydial conjunctivitis, given the prevalence of co-infection ^[11].